The present invention relates to a method and to a device for packing tubes which arrive continuously from a production line and by way of a grouping unit are arranged in groups of tubes lying next to one another with a settable unit number of tubes, which correspond to a layer of tubes to be deposited in a box.
Methods and devices which serve for grouping production units and packing them in boxes are known in many embodiments. The procedure with regard to the method as well as a suitable device in order to carry out such a method are in each case very dependent on the type of production units. Thus for example U.S. Pat. No. 5,732,536 shows a device by way of which adhesive tapes may be packed into boxes, the German published patent application DE-A-22 00 390 a device for packing for example household paper rolls, or EP-0 360 310 a device for packing flower pots. The handling of the most varied types of products accordingly necessitates various types of methods and devices, and even with products which appear to be of the same type, various problems may arise depending on the size or the design shape, and these problems demand differently adapted methods and devices.
The present invention relates to the packing of tubes. Here, one proceeds from a known device for forming product groups, as is for example known from EP-B-1 114 784. This device is in particular used for forming groups of elongate, cylindrical product units, such as sleeves of tubes or tins which arrive continuously from a production line, and are used for forming product groups with a preselectable unit number. The formed product groups on a conveying transport belt are brought into a push-off position and from there are pushed into a box in a layered manner. Devices of this type have proven to be extremely successful on the market, and operate with extraordinarily high cycle times. These machines have also been applied for packing tubes. If they are tubes of metal, then the tube body is relatively heavy with respect to the tube head, and the filling into the boxes is accordingly effected without any problem. The situation with tubes of plastic or laminates is more difficult. The ratio of the weight of the head of the tube to the weight of the body of the tube changes depending on the size of the tube. This is particularly the case with middle to small tube sizes. The ratio is additionally unfavorably influenced since the plastic tubes from the production lines are already delivered with the tube cap placed on, since these tubes in the delivered form after packing, are supplied to the respective firms for filling the tubes. Accordingly, the heads of the tubes which are thus delivered are almost always heavier that the sleeve-like tube body.
With all machines which are present on the market today, the tubes are pushed into a suitable box in a layered manner, wherein this box stands or lies on a side wall and accordingly the tubes are pushed into the box in a roughly horizontal direction. If then the tube heads are heavier than the sleeves, then the tubes which are already deposited in the box tend to tilt, so that the open sleeves directed to the grouping unit project slightly upwards beyond the actual plane which corresponds to the respective layer. The result of this is that subsequent layers abut such projecting tubes on insertion, and accordingly a disarrangement occurs, which leads to an immediate interruption of the method. This is extremely annoying, since these packing machines are mostly directly at the end of the respective production lines and thus an interruption on packing leads to an interruption of production too. As already mentioned, these problems are aggravated due to the fact that the respective closures have already been placed on the tube heads, and these closures furthermore have a smaller diameter than the sleeve itself. This encourages the previously described tilting movement.
A further problem lies in the fact that such plastic tubes and in particular plastic tubes of smaller dimensions very often serve for packing pharmaceutical products with which particular strict cleanliness rules exist. Accordingly, the packing machines described here, just as the production machines themselves are located in suitable clean rooms. This means that the tubes must either be packed in plastic boxes or one must use suitable plastic boxes which need to be lined with bag-like plastic film. Plastic tubes themselves as well as plastic boxes or the bag-like plastic film linings all tend to statically charge, by which means forces may occur by way of the static charging, even without the described tilting effect, which may lead to dislocations of the grouped units.